Problem with rosrun smach_viewer smach_viewer.py

[MortezaAliyari]

Hi,
I read the smach tutorial there is no problem until I run smach_viewer command.
Smach tutorial
rosrun smach_viewer smach_viewer.py
the terminal shows the below error :
[rospack] Error: package 'smach_viewer' not found
I checked the /opt/ros/noetic/share path there is no smach_viewer package. just smach.
the question is: What should I do to see the graphical representation of my smach code?
I'm using ubuntu focal, Noetic ROS, and python3.
thanks a lot for your support.

[StohanzlMart]

https://github.com/search?q=smach
https://github.com/ros-visualization/executive_smach_visualization/issues?q=noetic
https://www.google.com/search?channel=fs&client=ubuntu&q=ros+package+from+github

[StohanzlMart]

sudo apt-get update && sudo apt-get install -y ros-noetic-smach ros-noetic-smach-viewer